1. Technical Field
The present invention relates to crystals of Group III-V compounds and to methods of their manufacture, and more particularly relates to methods of manufacturing good-quality Group III-V compound crystal without producing cracks, even with the use of a variety of substrates, and to semiconductor devices manufactured employing the crack-free Group III-V compound crystal.
2. Description of the Related Art
Growing a crystal of a Group III-V compound, such as GaN crystal, on a substrate of a different material from the crystal material, such as a sapphire substrate or a silicon (Si) substrate, causes stress between the crystal and the substrate due to differences in properties such as their crystal lattice constants and thermal expansion coefficients, leading to warps and cracks; thus, the process does not yield Group III-V crystals of good quality.
In view of this problem, a method has been carried out for alleviating the stress between the crystals and the substrate by depositing a film of a silicon oxide (such as SiO2) on a sapphire substrate; patterning the silicon oxide film is by a technique such as photolithography, and thereafter growing a Group III-V crystal onto the patterned substrate. Such a method, however, is problematic in that it requires the patterning of the silicon oxide film, which means the manufacturing cost is high.